This invention generally relates to cable conduit devices and more particularly to inserts for use in connection with floors and the like for passage of cables from raceways through the insert device for convenient connection of telephone, electrical and other apparatus thereto. The insert assembly of the invention is designed for rapid, foolproof installation, without necessitating use of tools or special dexterity and is so designed and of such structural features as to provide automatic safeguards against installing it incorrectly.